The invention relates to a method for producing a surface structure, in particular on a surgical implant, in accordance with the preamble of claim 1, to a plant for carrying out the method and to uses of the method.
An implant which has anchoring surfaces for bone tissue is known from EP-A 0 417 034 (=P.6300). In this the anchoring surface is produced by means of a method in which three-dimensional geometric forms are produced using a high pressure liquid jet. In order to be able to achieve a suitable depth action with the liquid jet, abrasive particles are admixed to the liquid. These particles, traces of which remain in the depressions produced, must be compatible with the human body. In this known method it is assumed that with a high pressure jet which is linearly guided over a substrate, a groove-like ablation track arises in the substrate, the width of which is largely of the same size as the jet diameter or the diameter of the nozzle used.
The object of the invention is to create a method for producing a surface structure through material ablation by means of a liquid jet in which an ablation track arises which is particularly advantageous with respect to physiological processes as a result of the micro-structure or micro-topography which is produced. Such physiological processes are understood to include for example the growing on and in of bone tissue in a hip joint prosthesis or an electro-physiological influence on a tissue to be stimulated for example through a heart pacemaker electrode. This object is satisfied by the method which is characterized in claim 1.
In the method for producing a surface structure, material is ablated by means of a liquid jet. The jet is emitted from a nozzle under high pressure. In this an ablation location is controlledly moved on a surface of a substrate to be structured with the production of a predetermined macro-topography or a largely planar surface, namely through moving the nozzle and/or the substrate. The substrate is in particular part of a surgical implant. The liquid of the high pressure jet is emitted at a predetermined diameter d of the nozzle with a sufficiently high pressure p so that through the material ablation a linear track with quasi-fractal micro-topography is produced. In this the track width D is at least twice as large as d. Values for p and d are provided in the following range:
100 bar less than p less than 3000 bar and 0.1 mm less than d less than 10 mm;
or p greater than 3000 bar and d greater than 0.03 mm.
The method in accordance with the invention can also be advantageous in surface treatments in which non medical objects are treated:
a) the production of structures on homogeneous, quasi-isotropic materials in order for example to achieve a corrugation or an orange skin effect;
b) the structuring of inhomogeneous materials, with different behavior being used relative to solubility or erosion rates.
Subordinate claims 2 to 6 relate to advantageous embodiments of the method in accordance with the invention. The subject of claims 7 and 8 is a plant for carrying out the method. Claims 9 to 11 relate to uses of the method.